World weariness has nothing to do with age. Nor do you need to be old to show how loss has haunted you. In fact I'd even go so far to say that it can be more effective in a slightly younger character, because it's less expected.

I know this from personal experience. I had to deal with some pretty difficult and dramatic losses in my childhood, and by the time I was 10, I had a world weariness that people noticed all the time. I was constantly asked what was wrong, why I was upset. I was very much a haunted kid. It took me years of therapy and self-exploration to get that look off of my face. I'm sure that many who know me would say that I looked "older" then than I do now, because my internal attitude towards life has changed so much for the positive now that it shows on my face.

Because I've been through that, I've at times felt a little insulted each time I read a post saying that someone young can't portray world weariness as well as someone older. It's kind of like a slap in the face, that my experience and the pain I felt growing up isn't as valid simply because I was young.

I really appreciate you bringing this up, because if you hadn't, I know I eventually would have.